Composed of a single branch. When used in reference to an appendage, it usually implies the loss of the exopod, as in a walking leg [Warner, 1977].
Having a single branch (the endopodite) or ramus [Holdich and Jones, 1983].
With only a single branch [Wilson, 1989].
(Order Isopoda):
Having one ramus or branch [Kensley and Schotte, 1989].
(Subclass Copepoda):
One-branched; used of limbs possessing only one ramus (either endopod or exopod) [Boxshall and Halsey, 2004].
Crustacea glossary. Natural History Museum of Los Angeles County. 2011.